1. Field of the Invention
The present invention relates to an image projection device and an image projection method.
2. Description of the Related Art
An image projection device (typically, a projector) is known in which an image generating unit generates an image using light emitted from a light source based on image data transmitted from a personal computer, a digital camera, or the like, and the generated image is projected to a screen or the like through an optical system including a plurality of lenses. To facilitate adjustment of the image projection device at the time of its installation, a technique is known in which a relative position between an optical modulation element that modulates light emitted from the light source based on an image signal and a projection optical system that projects the light transmitted through the optical modulation element is changed.
For example, Japanese Laid-open Patent Publication No. 2014-134729 discloses a configuration to drive a relative movement mechanism configured to change, when a change in an attitude of a device body is detected, a relative position of an optical modulation element and a projection optical system such that the center of the base of a projected image and the optical axis of projected light coincide with each other in order to facilitate adjustment of a projector at the time of its installation.
Conventionally, however, illumination light to be irradiated to the optical modulation element needs to illuminate the whole area of a movable range of the optical modulation element. Therefore, there is a problem that an illumination efficiency of the illumination light is reduced because any area (which does not originally require illumination) other than the optical modulation element is also irradiated with the illumination light.